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Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
Japanese Journal of Applied Physics, 63(3), p.032005_1 - 032005_6, 2024/03
We introduce a novel gamma-ray imaging technique that uses detector response patterns. This method employs multiple shielding cubes randomly positioned in a three-dimensional configuration. Within the volume defined by these cubes, a unique gamma-ray flux pattern is formed based on the incidence direction of the gamma rays. This pattern can be measured using the responses of several scintillator cubes. By pre-measuring the detector response pattern and incidence direction of the gamma rays, the incidence direction can be estimated using an unfolding technique. Simulations were performed using a 
Cs point source. Our results show that a 10 MBq Cs source, located 3 m away from the imager, can be imaged with an angular resolution close to 10
. These findings suggest that our new method is comparable to existing gamma-ray imaging techniques. Potential applications of this imaging method include nuclear power plant decommissioning, nuclear medicine, security, and astronomy.
Kawahara, Rika*; Ochi, Kotaro; Yamaguchi, Katsuhiko*; Torii, Tatsuo*
Hoshasen (Internet), 48(2), p.43 - 48, 2023/04
The accident at the Fukushima Daiichi NPP resulted in a large amount of radioactive material being dispersed into the surrounding environment. It is important to understand the radiation distribution in the area, which is still located in the difficult-to-return zone. In this study, a Compton camera and an optical camera were combined to produce a three-dimensional distribution map of source locations and their intensities. Two locations in the difficult-to-return zone (Okuma town) were surveyed: a park parking lot and the area around a private house. The distribution of air dose rates was determined by measurements with a survey meter with a wand-type GPS (Gamma Plotter H manufactured by Nippon Radiation Engineering Co. Measurements were taken with a Compton camera (H420, H3D, USA) at several different positions and angles towards the hotspots. The software (Application Programming Interface Example) allowed real-time confirmation of the radiation incident information (incident time, energy, x, y, z) obtained by the Compton camera. By photographing hotspots in high-dose areas from different positions and angles, the location of the radiation sources and their spatial extent could be confirmed.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
KEK Proceedings 2022-3, p.46 - 53, 2023/01
The position of a streetlight can be predicted from the direction and shape of one's shadow projected on the street at night by the light of the streetlight. The application of this idea to gamma-ray imagers is known as coded aperture. In this study, we proposed the Coded Cube Camera - POrtable (C3PO), which has a three-dimensional shielding and scintillator crystal arrangement, and is composed of lead, scintillator, and depletion cubes randomly arranged in a 3
33 Rurik's cube shape, with each. The output of each scintillator produces a three-dimensional shadow pattern, which is returned to the source direction distribution by unfolding. In this study, we investigated the characteristics and feasibility of the system by simulation using Geant 4.
Sato, Yuki
Isotope News, (781), p.19 - 23, 2022/06
no abstracts in English
Sato, Yuki
Kensa Gijutsu, 27(5), p.9 - 15, 2022/05
no abstracts in English
Shikaze, Yoshiaki; Shimazoe, Kenji*
Journal of Nuclear Science and Technology, 59(1), p.44 - 54, 2022/01
Times Cited Count：3 Percentile：45.99(Nuclear Science & Technology)A Compton camera system for use on an unmanned helicopter was previously developed for characterizing the distribution of radioactive materials in highly contaminated areas. For this study, a small camera, a laser distance meter, an attitude angles sensor, temperature sensors, and real-time monitoring software were equipped to the Compton camera system to better measure flight parameters and to more precisely detect hot spot locations. To confirm if detection results were improved by the modifications, measurements were taken from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan). Ambient dose equivalent rate distributions at ground level were obtained by processing the flight data, then compared against measurements taken at ground level on foot using a survey meter. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude, and by restricting the deviation of the attitude angles. Between 6.0%-7.6% improvement in the position resolution was achieved by using the data from stable flight periods, even when using 1 minute data windows. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.
Sato, Yuki; Torii, Tatsuo
Nuclear Technology, 206(7), p.v - xvi, 2020/07
Times Cited Count：2 Percentile：24.28(Nuclear Science & Technology)Sato, Yuki; Torii, Tatsuo
Isotope News, (757), p.44 - 47, 2018/06
no abstracts in English
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scintillator Compton camera mounted on an unmanned helicopterShikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
Times Cited Count：37 Percentile：96.48(Nuclear Science & Technology)The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the 
-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).
Shikaze, Yoshiaki; Torii, Tatsuo; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; Yoshino, Masao*; Ito, Shigeki*; et al.
no journal, ,
no abstracts in English
Sonoda, Shinya*; Nabetani, Akira*; Kimura, Hiroyuki*; Kabuki, Shigeto*; Takada, Atsushi*; Kubo, Hidetoshi*; Kimura, Shotaro*; Sawano, Tatsuya*; Tanimori, Toru*; Matsuoka, Yoshihiro*; et al.
no journal, ,
We have developed the ETCC for new medical imaging device and succeeded in imaging the some medical imaging reagents. Thus, this detector is thought promising for a new medical imaging. The F-18 point-like and rod-like phantoms are measured with new ETCC, and the imaging performance was estimated. In addition, measurement of Tc-95m which is produced by Japan Atomic Energy Agency was performed.
rays by body tissue on the image of semiconductor Compton camera for nuclear medical useSakai, Makoto*; Kikuchi, Kimiko*; Torikai, Kota*; Arakawa, Kazuo*; Yamaguchi, Mitsutaka; Nagao, Yuto; Kawachi, Naoki; Fujimaki, Shu; Kamiya, Tomihiro; Odaka, Hirokazu*; et al.
no journal, ,
no abstracts in English
Sonoda, Shinya*; Nabeya, Akira*; Kimura, Hiroyuki*; Kabuki, Shigeto*; Takada, Atsushi*; Kubo, Hidetoshi*; Komura, Shotaro*; Tanimori, Toru*; Matsuoka, Yoshihiro*; Mizumura, Yoshitaka*; et al.
no journal, ,
SPECT and PET are widely used for medical imaging. However, radio isotopes available for SPECT and PET are limited. Under these circumstances, it is expected the appearance of the new imaging detector which can measure more various kinds of -ray sources in order to develop new biomarkers using new radio isotopes. We set out to contribute to medical imaging technology by developing Electron-Tracking Compton Camera (ETCC) which can measure the various radioactive medicine.
Sonoda, Shinya*; Nabetani, Akira*; Kimura, Hiroyuki*; Kabuki, Shigeto*; Takada, Atsushi*; Kubo, Hidetoshi*; Komura, Shotaro*; Sawano, Tatsuya*; Tanimori, Toru*; Matsuoka, Yoshihiro*; et al.
no journal, ,
We present the performance results using this new ETCC such as the imaging test using F-18 in point-like and rod-like phantoms with varying the intense of radiation. In addition, the measurementof Tc-95m which is produced by Japan Atomic Energy Agency was performed. Tc-95m emitsthe -rays with the energy, 204, 583, and 835 keV, and then an image with multi-energies is examined. The position resolution achieves less than about 8 degrees from 10 degrees at 511 keV by this improvement. Further improvement of the angular resolution (position resolution) will be presented until 2015 spring. Also, we are developing the next ETCC by increasing the thickness of the scintillator from 1 rad. to 2 rad. and the gas pressure from 1 atm to 3 atm which improvethe detection efficiency by a factor of 
5 at 511 keV. By these improvements, the imaging time of mouse is expected to be reduced from several hours with to 
20 minutes for lots of kinds of RIs with the energy band from 0.1-2 MeV.
Shikaze, Yoshiaki; Torii, Tatsuo; Nishizawa, Yukiyasu; Yoshida, Mami*; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; et al.
no journal, ,
no abstracts in English
Tc for Compton camera imagingHatsukawa, Yuichi; Tsukada, Kazuaki; Hashimoto, Kazuyuki; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Nagai, Yasuki; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.
no journal, ,
In recent years, the Compton camera which is originally developed for the astrophysical studies was applied for medical diagnostic usage. For the Compton camera imaging require technetium isotopes emitting higher energy -rays. Two Tc isotopes, Tc (T
= 60 d; E = 204, 582 and 835 keV) and 
Tc(T = 4.28 d, E = 778 and 812 keV) are candidates for Compton camera imaging. Compton camera imaging can realize high position resolution without collimator. Because of no collimator using, the Compton camera makes higher -ray detection efficiency. Compared with SPECT with 
Tc, the Compton camera imaging technique can be expected that radiation exposure deduce to 1/5-1/10. In this study, technetium-95m was produced by the 
Mo(p,n)Tc reaction.
Sato, Yuki; Kishimoto, Aya*; Kaburagi, Masaaki; Kataoka, Jun*; Torii, Tatsuo
no journal, ,
no abstracts in English
Sato, Yuki; Kaburagi, Masaaki; Terasaka, Yuta; Saegusa, Jun; Kawabata, Kuniaki; Wakaida, Ikuo; Torii, Tatsuo
no journal, ,
The development of radiation measurement methods in the high dose-rate environment is requested to accelerate implementation of decommissioning of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). We are now developing the technology which can measure the distribution of the contamination level with radioactive substances inside the building of FDNPP. Light-weight portable gamma camera is to be developed, and is used for drones that can remotely measure the radiation distributions in the high radioactive fields where workers are not allowed to enter and remain there.
Sato, Yuki; Ozawa, Shingo*; Izumi, Ryo*; Terasaka, Yuta; Kaburagi, Masaaki; Miyamura, Hiroko; Kawamura, Takuma; Tanifuji, Yuta; Kawabata, Kuniaki; Suzuki, Toshikazu*; et al.
no journal, ,
no abstracts in English
Sato, Yuki; Izumi, Ryo*
no journal, ,
no abstracts in English
